This document summarizes the results of a load flow analysis for interconnecting the electrical networks of two power generation areas, Process and Tank Loading. Ten load flow simulation cases were analyzed with different generation and loading scenarios. The best technical configuration was found to be two Process generators and one Tank Loading generator running with two interconnection lines. This provides adequate spinning reserve while allowing excess Process capacity to feed Tank Loading loads. The optimal tapping position for the isolation transformer between the networks was determined to be -5% based on the simulation results. Further protection coordination and switchgear rating studies are recommended before finalizing the interconnection plan.

1. International Journal of Applied Power Engineering (IJAPE)
Vol. 3, No. 1, April 2014, pp. 9~14
ISSN: 2252-8792  9
Journal homepage: http://iaesjournal.com/online/index.php/IJAPE
Load Flow Analysis for Process-Tank Loading Power
Generation Networks Interconnection
Radita Arindya
Satyagama University Jakarta, Indonesia
Article Info ABSTRACT
Article history:
Received Aug 14, 2013
Revised Dec 7, 2013
Accepted Jan 4, 2014
Establishment of interconnection links between Process-Tank Loading
electrical networks bring some advantages as there are excess capacity at
Process which can be utilized in principle to feed Tank Loading. Some result
of power system study will be as an input for operational purposes.
Concerning Motor Starting Studies and Load Flow Studies and taking into
account that the transformer is off load tap changing, the best tapping
position for Isolation Transformer is at -5% (primary side). The best
technical power generation configuration is proposed with configuration 2
(two) Process -TEG and 1 (one) Tank Loading-TEG running with 2 (two)
interconnection, provided with appropriate load shedding system. Bare in
mind that during smooth power transfer from each Process-TEG which
requires 3 (three) Process-TEG running in parallel, there is an issue on kA
capacity of Process switchgear. Existing setting of protection relay shall be
reviewed according to the result of protection coordination study.
Keyword:
Load flow analysis
Network interconnection
Power generation
Tank loading
Copyright © 2014 Institute of Advanced Engineering and Science.
All rights reserved.
Corresponding Author:
Radita Arindya,
Satyagama University Jakarta,
Indonesia.
Email: raditatech@yahoo.com
1. INTRODUCTION
The two electrical networks at Process -Tank Loading are not interconnected. As Tank Loading-
TEG power generation is less efficient and smaller capacity than Process one, it is more exposed to trip and
system instability problem. Therefore, electrical interconnection between Process -Tank Loading to increase
electrical network stability and reliability in tank loading and to avoid loss of production when 1 (one) tank
loading-TEG is unavailable. The idea of interconnection process-Tank Loading has been putting on the table
since Phase#1, but due to Tank Loading switchgear rating, instead of direct connection by cable, isolation
transformer shall be inserted as fault current limiter.
Hence, the excess capacity at Process can be utilized in principle to feed Tank Loading. This
solution will improve the process reliability of Tank Loading. After Process-Tank Loading interconnection
completion, decommissioning two Tank Loading TEGs is foreseen. Purpose of this document are electrical
power system studies regarding establishment and system behavior of Electrical Interconnection System
between Power Plant through isolation transformer. The studies are comprised as following Load Flow Study

2.  ISSN: 2252-8792
IJAPE Vol. 3, No. 1, April 2014 : 9 – 14
10
Based on progress meeting for Electrical Power System Study, cases and scenarios had been
defined, as described in the following clauses.
2. LOAD FLOW
There are ten cases for Load Flow Study, summarize as below:
LF Case:
Generator Interconnection
EventTank
Loading
Well Line A Line B
1 1 2 ON ON Loading on + CSU On
2 1 2 ON OFF Loading on + CSU On
3 1 3 ON OFF Loading on + CSU On
4 1 3 ON ON Loading on + CSU On
5 0 3 ON OFF Loading on + CSU On
6 0 3 ON ON Loading on + CSU On
7 2 2 ON ON Loading on + CSU On
8 2 2 OFF ON Loading on + CSU On
9 ? ? ON ON Loading only, and
minimum generation
10 3 0 ON OFF Start-up Process TEG,
with power from Tank Loading
Specific Limitation and Assumption for each Study
Load Flow Study:
 Generation at Process is simulated as isochronous (swing operation mode) and generation at Tank
Loading simulated as 5% droop (voltage control operation mode) with based load set at 1.8MW each
(voltage control operation mode)
 All Transformer is energized from HV side
 Tapping (off-load tap changer) of interconnection transformer are on primary side (or PROCESS side)
as per manufacturing drawing
 For Case#10, load at Process during black start assume at about 400kW

3. IJAPE ISSN: 2252-8792 
Load Flow Analysis for Process-Tank Loading Power Generation Networks (Radita Arindya)
11
3. LOAD AND POWER BALANCE
For Process, the final Power Balance figure is based on the latest observation trough DCS monitor at
Main Control Room, under the main Operational Office, for Tank Loading, will used existing documentation.
From document, generation and load consumption of Tank Loading and Process are summarized in table
below:
Area Installed Generator
Normal
Operation
Load
Tank Loading 6.6 MW (3x2.2 MW CENTAUR TEGs) 2x 4.7 MW
Process 27 MW (3x9 MW MARS TEGs) 2x 10 MW
Tank Loading load of 4.7 MW is including tanker loading operation and compressor running.
Process load of 10 MW (3 trains of gas turbine compressor, estimated total 1.5 MW). Power consumption of
Process excludes future water injection pumps), and smokeless Nitro flare (1MW).
The Process generation has capacity of 18 MW (2 TEGs in operation). With total Process load of 10
MW, at least 8 MW of spare generation capacity will be available at PPA. Hence, the excess capacity at
Process in principle can be utilized to feed Tank Loading.
Observation on Load and Power Balance at Process
The observation on Process Load and Generation:
Table 1: Process - Load and Power Balance – current operation
There is a small discrepancy between total load and total generation, as the observation is
sequentially noted from the figure displayed on the screen of the DCS, due to load fluctuation and accuration
of the measurement system.
From the historical graph report for a month period on power generation, showed that 3 (three)
generators were running with average power generation on each generator is about 2.6-2.7MW (or about
30% of its rated power). It means also that for PPA, only 1 (one) normal operating condition is occurred.
There are other loads which not running currently (like glycol reboiler); therefore for the purpose of
simulation of Load Flow, 10MW figure will be used, instead of 7.8MW (with some factor applied for each
glycol reboiler load). Hence, the final load and power balance of PROCESS as follow:
Calc
KW KVA P (KW) Q (KVar) Util (%)
Load at PPA :
1K-4550 LP Boostr 800KW 800 771 445 96%
1K-4820 Refrg. Compr. Train A - 1900KW 1,900 1,442 580 76%
1K-4920 Refregrant Comp. Train B - 1900KW 1,900 1,343 537 71%
1K-5020 St.by refrigernt Comp - 1900KW 1,900 1,442 580 76%
TR-9250A Load 1-LV-SB-100 bus A 2,500 253 63 10%
TR-9260A Load 1-LV-SB-101 bus A 2,500 148 140 8%
TR-9250B Load 1-LV-SB-100 bus B 2,500 364 275 18%
TR-9260B Load 1-LV-SB-101 bus B 2,500 262 112 11%
6-HV-SB 100 A 1,244 417
6-HV-SB 100 B 550 443
TOTAL LOAD 7,819
Generation at PPA :
1-G-9250-C Gas Turbine Generator C - 9MW 9,000 11,250 2,606 1,225 29%
1-G-9250-A Gas Turbine Generator A - 9MW 9,000 11,250 2,655 1,142 30%
1-G-9250-B Gas Turbine Generator B - 9MW 9,000 11,250 2,654 1,269 29%
TOTAL GENERATION 7,915
SPINNING RESERVE (2 GTG) 10,085
SPINNING RESERVE (3 GTG) 19,085
TAG # Designation
Rated Observation

4.  ISSN: 2252-8792
IJAPE Vol. 3, No. 1, April 2014 : 9 – 14
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Table 2: PROCESS - Load and Power Balance - for simulation purpose
Load and Power Balance at Tank Loading
Load and Power Balance at Tank Loading will be based on existing , which subject to different
operation scenario, which are:
 Loading Operation : 4,708 KW total load
 No Loading Operation : 3,508 KW total load
 Loading Operation and CSU Compressor Off : 4,168 KW total load
 No Loading Operation and Compressor Off : 2,968 KW total load
In general, for the purpose of simulation of Load Flow, 4.7MW figure will be used.
Load and Power Balance after Interconnection Process-Tank Loading
From the result of Load Flow Study, the brief Load and Power Balance after interconnection
Process-Tank Loading can be shown on table below:
Calc
KW KVA P (KW) Q (KVar) Util (%)
Load at PPA :
1K-4550 LP Boostr 800KW 800 771 445 96%
1K-4820 Refrg. Compr. Train A - 1900KW 1,900 1,442 580 76%
1K-4920 Refregrant Comp. Train B - 1900KW 1,900 1,343 537 71%
1K-5020 St.by refrigernt Comp - 1900KW 1,900 1,442 580 76%
TR-9250A Load 1-LV-SB-101 bus A 2,500 253 63 10%
TR-9250B Load 1-LV-SB-101 bus B 2,500 364 275 18%
TR-9260A Load 1-LV-SB-100 bus A 2,500 148 140 8%
TR-9260B Load 1-LV-SB-100 bus B 2,500 262 112 11%
6-HV-SB-100 A 1,244 417
6-HV-SB-100 B 550 443
TOTAL LOAD 7,819
Additional Load to be considered at PPA :
1-H-520G Glycol Reboiler 1-H-520G 1,000 730 73%
1-H-540G Glycol Reboiler 1-H-540G 1,000 730 73%
6-H-970G Glycol Reboiler 6-H-970G 1,000 730 73%
TOTAL LOAD (incl. GLYCOL REBOILER) 10,009
Generation at PPA :
1-G-9250-C Gas Turbine Generator C - 9MW 9,000 11,250 2,606 1,225 29%
1-G-9250-A Gas Turbine Generator A - 9MW 9,000 11,250 2,655 1,142 30%
1-G-9250-B Gas Turbine Generator B - 9MW 9,000 11,250 2,654 1,269 29%
TOTAL GENERATION 7,915
SPINNING RESERVE (2 GTG) 7,991
SPINNING RESERVE (3 GTG) 16,991
TAG # Designation
Rated Observation

5. IJAPE ISSN: 2252-8792 
Load Flow Analysis for Process-Tank Loading Power Generation Networks (Radita Arindya)
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Table 3: Load and Power Balance after Interconnection PPA-TANK LOADING
4. LOAD FLOW STUDIES
There were few studies regarding Load Flow on Process -Tank Loading interconnection before
project execution, This Load Flow Study result will confirm the above studies, subject to some
recommendations. The result of Load Flow will be used as reference for operational purpose such as setting
of Tap position for the Interconnection Transformer.
Summary of Load Flow Studies
Table 4: Summary of Load Flow Studies
Simulation Calc
TLA PCK
Produced
[MW]
(study)
Spinning
Reserve
PPA
(study)
TLA
(study)
1 1 2 20.2 14.812 5.388
TLA Loading On +
CSU On
10.076 4.736
2 1 2 20.2 14.818 5.382
TLA Loading On +
CSU On
10.077 4.741
3 1 3 29.2 14.814 14.386
TLA Loading On +
CSU On
10.072 4.742
4 1 3 29.2 14.811 14.389
TLA Loading On +
CSU On
10.073 4.738
5 0 3 27 14.904 12.096
TLA Loading On +
CSU On
10.076 4.828
6 0 3 27 14.841 12.159
TLA Loading On +
CSU On
10.077 4.764
7 2 2 22.4 14.774 7.626
TLA Loading On +
CSU On
10.076 4.698
8 2 2 22.4 14.770 7.630
TLA Loading On +
CSU On
10.076 4.694
9 0 2 18 14.032 3.968
Loading only (CSU off,
incl. its Utilities)
10.076 3.956
10 3 0 6.6 5.112 1.488
PPA Black Start w/
about 400kW load and
power from TLA
0.408 4.704
No
LOAD [MW]
Event
Generator
TOTAL
Gen
[MW]
TLA PCK Line A Line B
PPA
(study)
TLA
(study)
HV SB
(PPA)
HVS 11
(TLA)
1 1 2 ON ON
TLA Loading On +
CSU On
10.076 4.736 99.95% 100.00% -2.5% Tap on TX 2-1/2
2 1 2 ON OFF
TLA Loading On +
CSU On
10.077 4.741 99.95% 98.58% -2.5% Tap on TX 2-1
3 1 3 ON OFF
TLA Loading On +
CSU On
10.072 4.742 99.97% 98.60% -2.5% Tap on TX 2-1
4 1 3 ON ON
TLA Loading On +
CSU On
10.073 4.738 99.97% 100.00% -2.5% Tap on TX 2-1/2
5 0 3 ON OFF
TLA Loading On +
CSU On
10.076 4.828 99.96% 99.01% -5% Tap on TX 2-1
6 0 3 ON ON
TLA Loading On +
CSU On
10.077 4.764 99.96% 99.48% -2.5% Tap on TX 2-1/2
7 2 2 ON ON
TLA Loading On +
CSU On
10.076 4.698 99.96% 99.12% 0% Tap on TX 2-1/2
8 2 2 OFF ON
TLA Loading On +
CSU On
10.076 4.694 99.96% 98.26% 0% Tap on TX 2-1/2
9 0 2 ON ON
Loading only (CSU off,
incl. its Utilities)
10.076 3.956 99.95% 100.00% -2.5% Tap on TX 2-1/2
10 3 0 ON OFF
PPA Black Start w/
about 400kW load and
power from TLA
0.408 4.704 99.47% 100.00% 0% Tap on TX 2-1
No
V level (%)LOAD [MW]
Event
Interconn Lines Remark for
Transformer
Tapping
Position
Generator

6.  ISSN: 2252-8792
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5. CONCLUSION AND RECOMMENDATION
From the table#4 above, prelimininary conclusion are as follows:
 Process-Tank Loading interconnection through isolating transformer shown better performance of overall
system, such as: better voltage regulation, more flexibility in term of numbers of generation run especially
on Tank Loading side
 Operation of MK-6610 CSU (steady state) does not require all 3 (three) Tank Loading-TEG running
 Optimal tapping of Isolation Transformer is at +2.5% Tap (on primary side)
 Maximum voltage drop occurred in case#5, therefore adjustment on tapping to +5% Tap is required, but
subject to Off Load Tap Changer, tapping position must be decided at +2.5% Tap or +5% (on primary
side)
 Minimum generation configuration (with Tank Loading on Loading only operation) achieve by running
only 2 (two) TEG at Process with spinning reserve 3.968MW, so more economic operation can be
achieved
 Technically, the best generation configuration is 2 (two) PPA-TEG and 1 (one) Tank Loading-TEG., with
either 2 or 1 interconnection link
 The most reliable generation configuration is 2 (two) PPA-TEG and 2 (two) Tank Loading-TEG, with
either 2 or 1 interconnection link
 During Process start up using power from Tank Loading, all 3 (three) Tank Loading-TEG shall run
REFERENCES
[1] William D. Stevenson, Jr. Analisis Sistem Tenaga Listrik, Penerbit Erlangga, 1993.
[2] P. Van Harten (Setiawan). Instalasi Listrik Arus Kuat Jilid 1,2,3, Penerbit Bina Cipta, 1992.
[3] A.N. Afandi. EDSA : Software Aplikasi Tenaga Listrik, Penerbit Graha Ilmu 2010.